Brain asymmetry and dopamine: beyond motor implications in Parkinson's disease and experimental hemiparkinsonism
*Correspondencia: Dr. Manuel Ramírez Sánchez. Área de Fisiología. Universidad de Jaén. Edificio B3-263. E-23071 Jaén.
E-mail: msanchez@ujaen.es
Introduction: Brain asymmetry could be defined as the existence of functional, anatomic or neurochemical differences between both hemispheres. It is a dynamic phenomenon, regulated by endogenous and exogenous factors. Its functional significance is poorly clarified and is only partially understood in very specific cases such as the relationship between the lateralized brain content of dopamine and its motor effects which is specially patent in Parkinson's disease.
Development: The asymmetric brain content of dopamine not only displays lateralized motor effects but also behavioral and autonomic asymmetric consequences. In fact, Parkinson's disease is characterized not only by unilateral motor symptoms that arise at the early stages, but has other non-motor symptoms such as autonomic or cognitive alterations that are also revealed asymmetrically.
Conclusions: Brain asymmetry has been underestimated when analyzing the pathogeny of brain diseases and it has been partially studied only in some specific cases, such as Parkinson's disease. However, in order to appropriately understand some brain diseases such as Parkinson's disease, the need to consider this phenomenon has been highlighted.
Desarrollo El contenido asimétrico cerebral de dopamina no sólo da lugar a efectos motores lateralizados, sino que se extiende a consecuencias autonómicas y de conducta igualmente lateralizadas. De hecho, la enfermedad de Parkinson se caracteriza por síntomas motores unilaterales, que surgen en las fases iniciales de la enfermedad, y por otros síntomas no motores, como alteraciones autonómicas o cognitivas, que también se manifiestan de forma lateralizada.
Conclusiones La asimetría cerebral ha sido un aspecto infravalorado a la hora de analizar la patogenia de las enfermedades cerebrales, y sólo en determinados casos, como en la enfermedad de Parkinson, se ha profundizado parcialmente en su estudio. Sin embargo, se ha puesto en evidencia que es necesario considerar este fenómeno para la adecuada comprensión de algunas patologías cerebrales, como es el caso de la enfermedad de Parkinson.